Weight Watchers is surging

Weight Watchers shares are surging.

The stock climbed as much as 21% Friday after the company said Thursday that an Indiana University School of Medicine study found that adults with prediabetes lost significant weight after they used a Weight Watchers program.

The release cites previous research in saying that people with prediabetes can reduce their risk of developing type 2 diabetes by 58% if they lost up to 7% of their body weight.

From the company's statement:

The study found that those who participated in the prediabetes-specific Weight Watchers program lost significantly more weight than the control group at both six and 12 months. On average, Weight Watchers participants lost 5.5% of their body weight at six months and fully maintained that loss at 12 months, while the control group lost 0.8% of their body weight at six months and experienced slight regain for a loss of 0.2% of their body weight at 12 months.

The control group for the study was a group of people who received self-help advice on how to lose weight. And so, those who used Weight Watchers clearly had an edge, according to the study.

Weight Watchers shares have also recently been helped by news that Oprah Winfrey, who bought a stake in the company last October, announced that she had lost 26 pounds with the program.

Related to this, Gayle King - Oprah's long-time best friend, tweeted last Friday that she had lost 25 pounds since she started a Weight Watchers program last September.

The spikes in the stock still leave it down 20% for the past 12 months. Oprah's coming on board was part of the company's efforts to plug a decline in members.

Here's how the stock has traded over the past month, showing today's surge:

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